I own one of the pistols you are getting, and it's indeed a fine revolver. I measured the throats on my pistol (you can do this by slugging the throats, or by measuring with a internal ball gage set). You typically can't measure them with a dial caliper.
Anyway, my bore slugs .451-.452, and my throats slug ~.449. I chose to ream the throats to .4526. I have not had any trouble with the pistol. For what it's worth, I have another Ruger Bisley .45, with similar measurements, which I also reamed.
My opinion, you should be able to press your slugs thru the throats, with thumb pressure. If you can't, you should size your slugs smaller or make your throats bigger. I prefer to let the bore size the slugs, rather then relying on the slugs to "bump up" in diameter aftering be sized smaller in the throats.
This all applies to cast lead bullets only. I understand that jacketed bullets can be a different game, but I've never shot a jacketed bullet in a 45 Colt revolver.
HTH, Tom